1. Field of the Invention
The present invention relates generally to methods for forming Schottky diode contacts within microelectronics fabrications. More particularly, the present invention relates to methods for forming with low contact leakage Schottky diode contacts within microelectronics fabrications.
2. Description of the Related Art
Microelectronics fabrications are formed from microelectronics substrates over which are formed patterned microelectronics conductor layers which are separated by microelectronics dielectric layers. The patterned microelectronics conductor layers employed within microelectronics fabrications typically interconnect microelectronics devices which are in turn typically, but not exclusively, semiconductor integrated circuit microelectronics devices formed within and/or upon semiconductor substrates employed within semiconductor integrated circuit microelectronics fabrications.
When fabricating semiconductor integrated circuit microelectronics devices, there is often employed a metal layer (or metal silicide layer) to lightly doped semiconductor substrate layer contact, generally known as Schottky diode contact, for the purposes of forming semiconductor integrated circuit microelectronics device electrodes, as well as for other purposes generally related to the performance of the semiconductor integrated circuit microelectronics devices.
While Schottky diode contacts are thus desirable within the art of microelectronics fabrication, and in particular within the art of semiconductor integrated circuit microelectronics fabrication, Schottky diode contacts are often not formed entirely without problems within the air of microelectronics fabrication. In particular, it is often difficult to form within semiconductor integrated circuit microelectronics devices Schottky diode contacts which provide Schottky diode structures which exhibit sufficiently uniform or stable Schottky diode operating parameters, such as but not limited to a Schottky diode clamp voltage, to provide fully functional or reliable operation of a microelectronics fabrication within which is formed the semiconductor integrated microelectronics device employing the Schottky diode contact which provides the Schottky diode structure exhibiting the insufficiently uniform or stable Schottky diode operating parameters.
It is thus towards the goal of forming within microelectronics fabrications in general, and within semiconductor integrated circuit microelectronics fabrications more particularly, Schottky diode contacts which provide Schottky diode structures which exhibit uniform and stable operating parameters that the present invention is directed.
Various methods have been generally disclosed for forming metal to semiconductor substrate contacts within semiconductor integrated circuit microelectronics fabrications and more particularly for forming metal to lightly doped semiconductor substrate Schottky diode contacts within semiconductor integrated circuit microelectronics fabrications.
For example, Friedman et al., in U.S. Pat. No. 4,233,337, discloses a method for selectively forming multiple series of metal to silicon semiconductor substrate layer contacts employing differing metallization layers formed upon a single semiconductor substrate within a semiconductor integrated circuit microelectronics fabrication. The method employs a series of thermal silicon oxide mask layers formed upon a series of contact regions of a silicon semiconductor substrate, where at least a first group of thermal silicon oxide mask layers is additionally masked with a photoresist layer to allow hydrofluoric acid etching of a second group of photoresist unmasked thermal silicon oxide layers prior to forming a metal contact layer upon portions of the semiconductor substrate exposed after hydrofluoric acid etching of the second group of thermal silicon oxide mask layers. The photoresist layer may then be removed from at least the first group of thermal silicon oxide mask layers and the first group of thermal silicon oxide mask layers may similarly be etched prior to forming a different metal contact layer upon portions of the semiconductor substrate exposed after hydrofluoric acid etching of the first group of thermal silicon oxide layers.
In addition, Morris, in U.S. Pat. No. 5,021,840, discloses a method for forming with attenuated contact leakage a Schottky diode contact with a silicon semiconductor substrate within a semiconductor integrated circuit microelectronics fabrication. The method employs a dielectric sidewall spacer layer formed adjoining a sidewall of a patterned dielectric layer which defines the Schottky diode contact region within the silicon semiconductor substrate and upon which Schottky diode contact region a platinum silicide anode layer is formed, where the dielectric sidewall spacer layer attenuates isotropic sidewall etching of the patterned dielectric layer which may otherwise lead to contact leakage of the Schottky diode contact at the periphery of the platinum silicide anode layer.
Finally, Robinson et al., in U.S. Pat. No. 5,268,316, discloses a method for fabricating a Schottky diode structure within a semiconductor substrate, where the Schottky diode structure employs: (1) a localized diode well as a substrate for a Schottky diode contact; (2) a buried diode interconnection layer; and (3) a diode ohmic contact region. Each of the localized diode well, the buried diode interconnection layer and the diode ohmic contact region is formed simultaneously with a corresponding structure employed within a bipolar metal oxide semiconductor field effect transistor (FET) structure formed simultaneously with the Schottky diode structure.
Desirable within the art of microelectronics fabrication are additional methods which may be employed for forming within microelectronics fabrications Schottky diode contacts which provide Schottky diode structures with uniform and stable operating parameters, such as but not limited to Schottky diode clamp voltages.
It is towards that goal that the present invention is directed.